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Author: Nathan O'Brennan
To: Main PLUG discussion list

Would SELinux protect in any way against either of these

On 2018-01-12 00:18, Joseph Sinclair wrote:
> Feel free to repost anywhere. I don't have a blog site I use; so no
> real place to post a full article...
> On 2018-01-11 07:24 PM, Aaron Jones wrote:
>> Thanks Joe.
>> You should blog an article about this cuz that was the best
>> explanation for the issue I have read so far.
>>> On Jan 11, 2018, at 6:42 PM, Joseph Sinclair
>>> <> wrote:
>>> There seems to be a lot of confusion surrounding the recently
>>> disclosed CPU hardware issues...
>>> A few points to consider:
>>> 1) This is a cache timing attack using speculative execution (a key
>>> performance feature in the hardware) that exposes data (i.e. it's not
>>> an exploit to "take over" a system); it can only read memory, and
>>> only VERY slowly, while thrashing the heck out of the CPU.
>>> 2) Abusing speculative execution is literally something nobody
>>> thought of doing until a few years ago.
>>> 3) The researchers spent an immense amount of time figuring out
>>> tactics that worked, time no hardware design engineer would ever have
>>> had available, assuming that engineer even had the knowledge to do
>>> the coding required (hint: they don't).
>>> 4) Exploiting these flaws is HARD. It requires native code
>>> execution, careful and highly skilled coding, specific targeting of
>>> the memory to be read, and a lot of time on the target machine
>>> without tripping alarms due to CPU use.
>>> 5) The major concern here is things like VM farms because this allows
>>> untrusted code in a guest to (very slowly) read memory from the host
>>> or other guests. It's possible to use in other contexts, but the
>>> cost/benefit balance is pretty bad; desktops and other targets are
>>> far easier to exploit with well-known and widely used "social" hacks.
>>> Lacking the full detail, I would venture that this *type* of exploit
>>> is possible (in some form) for every Intel CPU since the original
>>> Pentium PRO which introduced speculative execution to the Intel
>>> architecture.
>>> We don't need to replace hardware, fortunately, this specific set of
>>> tactics can be mitigated by having the Kernel (along with microcode,
>>> aka firmware) set flags in the CPU to force a full context switch in
>>> the specific situations identified by the researchers.
>>> Yes, mitigation slows down execution a bit; basically the IPC for
>>> Intel chips now roughly matches the IPC for AMD chips which always
>>> forced the context switch (due to a different design balance).
>>> I would venture that this flaw is actually caused by Intel having
>>> such a heavy focus to achieve (and maintain) higher IPC levels than
>>> AMD, and cutting a (seemingly benign) corner to accomplish that.
>>> A bit of inside-baseball here:
>>> Every digital design engineer looks for what we call "don't cares"
>>> segments of the boolean map where the logic value has no impact on
>>> the "correctness" of the result.
>>> Those are places where we can cut gate count or speed up execution.
>>> Avoiding a context switch in a CPU with the Intel design for 3 layer
>>> caching is one of those areas where "don't cares" can show up.
>>> My gut feel is that the Intel engineers saw an opportunity to retain
>>> "correct" execution of code while speeding up speculative execution
>>> by skipping the context switch until it was actually necessary (e.g.
>>> the speculative branch became "live").
>>> It is exactly the kind of thing I can see a really smart engineer
>>> doing because, without future knowledge, it's actually the right
>>> thing to do.
>>> You get faster execution without any added cost and without breaking
>>> existing code.
>>> That, in retrospect, was a mistake that allowed a very sophisticated
>>> attacker to read a few bits of unauthorized memory in a very sneaky
>>> manner.
>>> That someone, a decade or two after the design arose, discovered a
>>> way to misuse that design isn't a sign of malice or malpractice; it's
>>> a sign that security researchers are getting REALLY good at finding
>>> unexpected ways to use hardware design against security.
>>> P.S.
>>> That reddit article is utter garbage.
>>> Yes, there is, on some motherboards, a Management Engine which is a
>>> *separate* CPU, is mostly present only on "business" and server
>>> motherboards, and has NOTHING TO DO WITH the recent exploits. The
>>> FSF and others have been warning about that particular bit of
>>> hardware for a long time.
>>> The ME has valuable functionality that makes sense for servers
>>> especially, and for business-owned machines in general (mostly remote
>>> system management, particularly lights-out management).
>>> The ME was added to the system at the request of business customers
>>> so they could remotely access machines owned by the business (even if
>>> turned off) and either manage their servers or ensure the main O/S
>>> and applications were kept in compliance with policy on desktops.
>>> Every motherboard I've seen with an ME (and only some have one) can
>>> disable the ME; usually with a jumper or switch on the board.
>>> As I understand things it was actually government buyers who demanded
>>> the ability to disable the ME (originally it couldn't be disabled),
>>> because government agencies are targets far more often than they are
>>> attackers.
>>>> On 2018-01-11 10:36 AM, wrote:
>>>> This is basic stuff. Kernel memory must be segregated and each
>>>> application's memory must be segregated. These are the basics of
>>>> CPU
>>>> functionality. That is why I find theses issues perplexing. And it
>>>> leads me to one basic question. If these problems persisted since
>>>> 1995,
>>>> how could these issue go undetected until recently when multiple
>>>> separate groups discovered these flows? AND is it possible others
>>>> have
>>>> found and used these flaws for their own gain?
>>>> No matter what happened, politics, accident... etc We have a HUGE
>>>> problem. Even if there were CPUs that were not vulnerable, it would
>>>> take years to replace all computers that are publicly facing. In
>>>> the
>>>> mean time there are some seriously evil people / groups / countries
>>>> that
>>>> will be looking into how they can use theses chip bugs /
>>>> vulnerabilities
>>>> / features... to further their goals.
>>>>> From what I can tell the solution is to use software - the kernel
>>>>> to fix
>>>> or patch the shortcomings of these CPUs. A software patch to fix
>>>> hardware. This is very scary. A software patch can be removed and
>>>> / or
>>>> replaced, leaving the host vulnerable.
>>>>> On 2018-01-11 10:10, Mark Phillips wrote:
>>>>> No, I don't work at Intel. I am, however, not a believer in all the
>>>>> government conspiracy theories floating around the Internet.
>>>>> Mark
>>>>> On Thu, Jan 11, 2018 at 9:25 AM, Aaron Jones <>
>>>>> wrote:
>>>>> Signals intelligence is believed to have been birthed in 1904.
>>>>> But exploiting hardware isn't new. For military, police, or
>>>>> criminal intentions.
>>>>> You work at Intel Mark? Lol
>>>>> On Jan 11, 2018, at 9:11 AM, Mark Phillips
>>>>> <> wrote:
>>>>> There is no conspiracy here. 23 years ago no one thought about
>>>>> attack vectors and how to take over machines. It is only recently
>>>>> that we are all sensitized to this problem. Even though the tech
>>>>> world is sensitized to the nature of exploits, companies still ship
>>>>> brand new products (e.g. Nest, cars, etc.) that can be exploited by
>>>>> almost anyone. It was only recently that router and switch
>>>>> companies stopped using admin and admin as login credentials!
>>>>> Your argument that these new CPU exploits are a government
>>>>> conspiracy can be applied to any potential exploit discovered today
>>>>> in a piece of code written yesterday.
>>>>> Mark
>>>>> On Thu, Jan 11, 2018 at 9:02 AM, Carruth, Rusty
>>>>> <> wrote:
>>>>> As mentioned earlier, I've done my share of ... um, looking for
>>>>> flaws in design of operating systems back when I was in college.
>>>>> (What, 1976?)
>>>>> We discovered some bad flaws in the design of the <redacted>. How
>>>>> long had the Univac been around? I don't know, but a while.
>>>>> Unless someone with WAY too much time on their hands is actively
>>>>> seeking ways around stuff, there's only so much 'bug' you can find.
>>>>> (and, actually, you really need more than one person involved
>>>>> (partially so someone can ask the 'right' stupid question :-))
>>>>> Doesn't take malice or sloppiness, and I will say being a
>>>>> publicly-traded company makes it very hard to spend the time
>>>>> required to even start on the hacking required (Being
>>>>> publically-traded makes your owner effectively insane, since your
>>>>> owner is actually many people, all with different and often
>>>>> diametrically opposing goals for the company).
>>>>> Anyway, tell you what - go read the Intel hardware docs and see if
>>>>> you can find the info needed to put together to see the bug. And
>>>>> this with prior knowledge of where to look.
>>>>> I will say that this doesn't excuse much, but realize that being a
>>>>> public company drives you insane ;-)
>>>>> Rusty
>>>>> -----Original Message-----
>>>>> From: PLUG-discuss []
>>>>> On Behalf Of
>>>>> Sent: Thursday, January 11, 2018 8:42 AM
>>>>> To: Main PLUG discussion list
>>>>> Subject: Re: Post : INTEL'S SECURITY FLAW IS NO FLAW
>>>>> ...
>>>>> I've read these issues may have persisted as far back as 1995. How
>>>>> does
>>>>> that happen? How does an army of engineers miss this for 23 years?
>>>>> How
>>>>> do you explain that?
>>>>> That means lots of people came and went. There should have been
>>>>> lots of
>>>>> QA... for 23 years.
>>>>> How does this happen? Only two ways I can see 1) sloppy work, or
>>>>> 2)
>>>>> intentionally.
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